Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Big Island | Island | 171 | Rock Island | 41 27 40 N | 090 36 13 W |
| Big Island (historical) | Island | 131 | Scott | 39 35 25 N | 090 33 37 W |
| Big Island School (historical) | School | 171 | Rock Island | 41 27 53 N | 090 36 16 W |
| Big Lake | Lake | 142 | Adams | 39 52 12 N | 091 24 52 W |
| Big Lake | Lake | 131 | Brown | 39 58 02 N | 090 31 19 W |
| Big Lake | Lake | 138 | Cass | 40 03 31 N | 090 08 58 W |
| Big Lake | Lake | 136 | Clinton | 38 43 30 N | 089 28 20 W |
| Big Lake | Lake | 133 | Fulton | 40 27 56 N | 089 54 53 W |
| Big Lake | Lake | 98 | Gallatin | 37 43 51 N | 088 06 31 W |
| Big Lake | Lake | 132 | Schuyler | 40 04 30 N | 090 24 36 W |
| Big Lake School (historical) | School | 110 | Jackson | 37 45 48 N | 089 32 09 W |
| Big Marsh | Swamp | | Cook | 41 41 17 N | 087 34 00 W |
| Big Mound Cemetery | Cemetery | 268 | Ogle | 42 04 46 N | 089 06 34 W |
| Big Mound Drainage Ditch | Canal | 115 | Wayne | 38 19 46 N | 088 25 13 W |
| Big Muddy Creek | Stream | | Clay | 38 38 16 N | 088 17 46 W |
| Big Muddy Island | Island | 104 | Jackson | 37 34 36 N | 089 29 39 W |
| Big Muddy Post Office (historical) | Post Office | 128 | Franklin | 37 54 49 N | 089 02 40 W |
| Big Muddy River | Stream | | Jackson | 37 34 25 N | 089 31 01 W |
| Big Muddy Subimpoundment Dam | Dam | 122 | Jefferson | 38 10 39 N | 089 00 06 W |
| Big Neck Post Office (historical) | Post Office | 208 | Adams | 40 09 19 N | 091 07 36 W |
| Big Negro Creek | Stream | | Warren | 40 42 30 N | 090 33 20 W |
| Big Oak Campground | Locale | 121 | Jackson | 37 46 46 N | 089 22 59 W |
| Big Oak Shopping Center | Locale | 234 | Kane | 42 02 06 N | 088 17 44 W |
| Big Prairie Cemetery | Cemetery | 123 | White | 38 03 00 N | 088 06 20 W |
| Big Prairie School | School | 123 | White | 38 02 58 N | 088 06 25 W |
| Big Ridge | Ridge | 128 | Saline | 37 43 39 N | 088 27 46 W |
| Big Ridge Church | Church | 125 | Saline | 37 43 41 N | 088 28 06 W |
| Big River State Forest | Forest | 188 | Henderson | 41 00 37 N | 090 54 45 W |
| Big Rock | Populated Place | 216 | Kane | 41 45 50 N | 088 32 49 W |
| Big Rock Creek | Stream | | Kendall | 41 38 00 N | 088 32 17 W |
| Big Rock Elementary School | School | 215 | Kane | 41 45 53 N | 088 32 46 W |
| Big Rock Post Office | Post Office | 216 | Kane | 41 45 48 N | 088 32 49 W |
| Big Rock School (historical) | School | 173 | Madison | 38 54 10 N | 089 43 40 W |
| Big Run Acres | Populated Place | 216 | Cook | 41 38 49 N | 088 01 31 W |
| Big Run Golf Club | Locale | 209 | Will | 41 38 25 N | 088 02 18 W |
| Big Saline Church | Church | 117 | Saline | 37 39 56 N | 088 27 25 W |
| Big Saline Church Cemetery | Cemetery | 129 | Saline | 37 39 51 N | 088 27 17 W |
| Big Sandy Creek | Stream | | Scott | 39 33 04 N | 090 34 23 W |
| Big Sink | Basin | 116 | Hardin | 37 30 22 N | 088 11 15 W |
| Big Sister Creek | Stream | | Fulton | 40 22 46 N | 090 01 49 W |
| Big Sky Park | Park | 253 | McHenry | 42 11 23 N | 088 20 11 W |
| Big Slough | Stream | | Henry | 41 35 02 N | 090 10 59 W |
| Big Slough | Stream | | Lawrence | 38 33 21 N | 087 40 11 W |
| Big Slough | Stream | | McLean | 40 38 16 N | 088 56 44 W |
| Big Slough (historical) | Swamp | 190 | Kendall | 41 38 07 N | 088 22 28 W |
| Big Slough Ditch | Canal | 183 | Henry | 41 33 09 N | 090 02 10 W |
| Big Spring Post Office (historical) | Post Office | 196 | Shelby | 39 17 32 N | 088 33 49 W |
| Big Swan Lake | Swamp | 126 | Clinton | 38 31 26 N | 089 24 20 W |
| Big Swan Pumping Station | Locale | 131 | Scott | 39 34 48 N | 090 34 55 W |
| Big Swan School (historical) | School | 128 | Scott | 39 34 48 N | 090 33 33 W |
| Big Three School (historical) | School | 197 | Fayette | 39 11 16 N | 089 08 02 W |
| Big Timber Lake | Reservoir | 179 | Peoria | 40 42 36 N | 089 40 54 W |
| Big Timber Lake Dam | Dam | 179 | Peoria | 40 42 36 N | 089 40 54 W |
| Big Timber Scout Camp | Locale | 268 | Kane | 42 04 08 N | 088 21 15 W |
| Big Woods (historical) | Woods | 234 | Kane | 41 48 44 N | 088 17 25 W |
| Big Woods Cemetery | Cemetery | 226 | DuPage | 41 49 05 N | 088 13 49 W |
| Big Woods Church | Church | 226 | DuPage | 41 49 05 N | 088 13 55 W |
| Big Woods County Forest Preserve | Park | 228 | DuPage | 41 48 55 N | 088 14 22 W |
| Big Woods Park | Park | 237 | Kane | 41 50 12 N | 088 17 26 W |
| Big Woods School (historical) | School | 226 | DuPage | 41 49 07 N | 088 13 51 W |
| Big Zion Missionary Baptist Church | Church | 183 | Cook | 41 46 33 N | 087 38 17 W |
| Bigelow House (historical) | Building | 181 | Cook | 41 52 45 N | 087 37 46 W |
| Biggs | Populated Place | 151 | Mason | 40 14 29 N | 089 54 15 W |
| Biggs Ditch | Canal | 151 | Mason | 40 13 30 N | 089 54 15 W |
| Biggsville | Populated Place | 209 | Henderson | 40 51 13 N | 090 51 54 W |
| Biggsville Cemetery | Cemetery | 207 | Henderson | 40 52 00 N | 090 51 55 W |
| Biggsville Quarry | Mine | 154 | Henderson | 40 51 22 N | 090 52 51 W |
| Biggsville United Methodist Church | Church | 208 | Henderson | 40 51 08 N | 090 51 54 W |
| Biggsville United Presbyterian Church | Church | 205 | Henderson | 40 51 14 N | 090 51 56 W |
| Bigham School (historical) | School | 133 | Perry | 38 01 09 N | 089 27 34 W |
| Bigley Cemetery | Cemetery | 129 | Massac | 37 10 20 N | 088 35 25 W |
| Bigneck | Locale | 205 | Adams | 40 08 15 N | 091 09 21 W |
| Bigneck Creek | Stream | | Adams | 40 07 08 N | 091 13 29 W |
| Bill Hill Hollow | Valley | | Saline | 37 36 23 N | 088 38 12 W |
| Bill Hollins Dancing Studio | School | 181 | Cook | 41 46 34 N | 087 35 32 W |
| Bill Young Park | Park | 213 | Cook | 41 36 44 N | 087 52 04 W |
| Billett | Populated Place | 128 | Lawrence | 38 39 52 N | 087 39 08 W |
| Billett School (historical) | School | 138 | Lawrence | 38 40 27 N | 087 40 11 W |
| Billett United Methodist Church | Church | 128 | Lawrence | 38 39 49 N | 087 39 09 W |
| Billings Lake | Lake | 129 | Morgan | 39 52 00 N | 090 34 45 W |
| Bills Creek | Stream | | Shelby | 39 19 38 N | 088 34 21 W |
| Bills Run | Stream | | Grundy | 41 20 26 N | 088 28 55 W |
| Billsbach Lake | Lake | 134 | Marshall | 41 05 07 N | 089 21 40 W |
| Billy Caldwell Golf Course | Locale | 187 | Cook | 41 59 33 N | 087 45 47 W |
| Billy Jones Elementary School | School | 126 | St. Clair | 38 37 03 N | 090 08 34 W |
| Biltmore Country Club | Locale | 251 | Lake | 42 11 59 N | 088 08 07 W |
| Bilyeu Cemetery | Cemetery | 184 | Christian | 39 37 31 N | 089 05 00 W |
| Binder School (historical) | School | 222 | DeKalb | 41 44 25 N | 088 38 59 W |
| Bingham | Populated Place | 183 | Fayette | 39 06 51 N | 089 12 48 W |
| Binghampton | Populated Place | 229 | Lee | 41 43 00 N | 089 18 14 W |
| Binghampton Cemetery | Cemetery | 227 | Lee | 41 43 09 N | 089 18 38 W |
| Bingman Station | Populated Place | 134 | White | 38 04 59 N | 088 14 41 W |
| Binney | Populated Place | 185 | Madison | 38 59 24 N | 089 43 38 W |
| Binnie County Forest Preserve | Park | 274 | Kane | 42 07 27 N | 088 21 26 W |
| Binnie Hills | Populated Place | 276 | Kane | 42 07 16 N | 088 21 49 W |
| Binnie Lakes | Populated Place | 276 | Kane | 42 06 59 N | 088 21 34 W |
| Biological Sciences Learning Center | Building | 180 | Cook | 41 47 31 N | 087 36 11 W |
| Birch Branch | Stream | | Jo Daviess | 42 26 44 N | 090 02 20 W |
| Birch Creek | Stream | | Cumberland | 39 16 05 N | 088 04 01 W |
| Birch Creek | Stream | | Greene | 39 26 40 N | 090 16 10 W |
| Birch Creek | Stream | | Lawrence | 38 47 23 N | 087 42 13 W |
| Birch Island | Populated Place | 133 | Calhoun | 39 07 53 N | 090 40 52 W |
| Birch Park | Park | 230 | Cook | 42 02 47 N | 088 04 13 W |
| Birch School (historical) | School | 156 | Greene | 39 27 19 N | 090 16 26 W |
| Birchlers Lake | Reservoir | 171 | Randolph | 37 55 48 N | 089 48 42 W |
| Birchlers Lake Dam | Dam | 171 | Randolph | 37 55 48 N | 089 48 42 W |
| Birchwood (subdivision) | Populated Place | 182 | Cook | 42 01 00 N | 087 39 55 W |
| Birchwood Park | Park | 226 | Cook | 42 05 40 N | 088 03 22 W |
| Birchwood Park | Park | 233 | DuPage | 41 45 26 N | 087 59 02 W |
| Birchwood Park | Park | 223 | Tazewell | 40 42 35 N | 089 23 39 W |